Universal joint



2 y 1941- v E. w. JOHNSON 2,242,215

. UNIVERSAL JOINT Filed Feb. 14. 1939 Eda/in M elbkms'on/ Patented May 20, 1941 UNIVERSAL JOINT Edwin W. Johnson, Trumbull, Conn, assignor to The Singer Manufacturing Company, Elizabeth, N. 3., a corporation of New Jersey Application February 14, 1939, Serial No. 256,324

3 Claims.

This invention relates to universal joints adapted especially for use in sewing machine pitman connections and has forits primary object to provide an inexpensive and simple construction designed to simplify the eradication of inaccuracies of fitwh-ich have heretofore been difficult and expensive to deal with on a mass production basis.

A further object of the present invention is the provision of a power-transmitting connection having intermediate its ends a universal joint which can be manufactured easily and accurately with the aid of simple machining operations and a commercial hardened steel ball.

Prior to the present invention it has been common practice in the manufacture of power transmitting connections such as pitmans, which are adapted to transmit power at an angle to the planes of action of the pitman driving and driven elements, to employ the so-called ball-and-socket connection at either or both ends of the connection. In these devices the ball element is turned down on a'lathe or similar machine and it is well known that the production of a' ball in this manner is an expensive machining operation and is diflicult of accurate consummation. In the present pitman, the construction and method of manufacture of which will hereinafter be described in detail, only simple machining operations are required to provide suitable sockets in the connection members for a steel ball which can be purchased commercially in large quantities at a relatively low cost per ball.

For a betterunderstanding of the present invention reference may be had to the accompanying drawing, in which i Fig. 1 is a side elevation of a pitman embodying the present invention.

Fig. 2 is an end elevation of Fig. 1.

Fig. 3 represents an enlarged vertical sectional view, taken substantially along the line 33, Fig. 2.-

Fig. 4 is a disassembled perspective view of the universal Joint of the pitman, illustrating the relative position of the various parts which constitute the Joint.

Fig. 5 is a vertical sectional view of one of the pitman sections, showing the shape of the ballreceiving socket after the drilling thereof and beforethe hardened steel ball has been pressed into the socket to provide a working seat for the ball. 7

Fig.6 is a view similar to Fig. 5, except that the ball'has been pressed into the socket and a working seat. has been formed therefor.

a hardened commercial steel ball I.

As disclosed in the drawing, the power transmitting connection selected. for illustration purposes only, comprises-aerank-arm section I and a lower pitman section j1--. The crank-arm section I, at its upper end, is prferably formed with a split head 3 which 'isadapted to be frictionally clamped by means ofta' screw 4 upon a shaft or other element (not ;.jshown) of the machine to be driven by the pitman, The pitman 2, at its lower end, is preferably formed with a cylindrical strap 5 engaging an eccentric 6 secured upon a suitable actuating shaft 1. I It will be understood that the specific construction of the remote ends 3 and 5 of the power transmitting connection are not intended to limit the invention set forth in the appended claims, but are chosen merely to dis-' close a practical form of connection. It will be understood also that the present invention may be incorporated in many different types of power transmitting connections where it is desirable to use a universal joint intermediate the ends of the connection.

Referring now to the universal bail-joint, it will be observed that the sections or members I and 2 have their adjacent end-portions formed into cylindrical heads 8 and 9 which are disposed in overlapping relation. Formed in the adjacent or inner faces Ill and II of the cylindrical heads 8 and 9 are oppositely disposed conical sockets l2 and I3 which are adapted to receive between them The diameter of the steel ball l4 and the sockets l2 and I3 are preferably of such size that the adjacent faces l0 and ll of the cylindrical heads 8 and 9 are maintained spaced apart a distance permitting limited universal movement of one member relative to the other member.

The two cylindrical heads 8 and 9 of the memhers I. tnd 2 are held in contact with the interposed steel ball I! by means of a retaining arm 15 which is detachably secured upon the pitman member '2 by the screw Ii. This retaining arm 15 has threaded into it anladjusting screw it, the inner end of which is cupped and engages the semispherically formed outer surface I! of the cylindrical head 8. In order that the crank-arm section I may move relative to pitman member 2 and about the steel ball it without binding, the radius of curvature of the semispherical surface l1, represented by R in Fig. 3, passes through the center of the steel ball ll. When constructed 1 in this manner the sem-ispherical surface II is concentric with the periphery of the ball I4, and thus the crank-arm section I can move readily about the steel ball II and beneath the retaining arm II.

In view of the simplicity of construction of the present universal joint, as somewhat novel method can be followed in the manufacture of the same. The method preferably to be followed comprises. first, drilling into the cylindrical heads I and. O the bail-receiving sockets i2 and I3 and, secondly,

before the members I and 2 have been hardened,

placing the commercial steel ball ll into the sockets and applying sufficient pressure upon the cylindrical heads of the pitman sections to force or sink theball into the softer metal so as to form a spherical ball-seat II therein. Subsequently, the members I and 2 can be hardened without affecting the shape of the ball-receiving sockets. It will be understood that the conical sockets I2 and II can be drilled successively with a conventional centering drill or any other common form of drill having the correct cutting-face angle. Obviously, the provision of the spherical seat It lengthens the life of the universal joint, inasmuch as it provides surface contact between the ball and each socket. Without such a seat the ball would engage each socket along line wutact only and, after some use, play which would develop between the ball and sockets would render the connection too noisy for practical use.

From the foregoing description, it will be understood that I have provided a universal joint for power transmitting connections which can be produced with the aid of a simple drilling operation and a commercial steel ball. Further, I have provided a power transmitting connection having a universal joint between two members thereof, which joint can be assembled accurately and expeditiously.

It will be obvious that the present invention is susceptible of some change and modification without departing from the spirit thereof and for this reason I do not wish to be understood as limiting the invention to the precise arrangement and formation of the several parts herein shown and described except as hereinafter claimed.

Having thus set forth the nature of the invention, what I claim herein is:

l. A power transmitting connection comprising two members each of which has a ball-receiving socket opening into the inner face thereof, a ball interposed between said ball-receiving sockets. one of said members having formed upon its outer face and concentric with said ball a semispherical surface, and a retaining arm secured upon one of said members and engaging the semispherical surface of the other member for maintaining said members in contact with said ball.

2. A power transmitting connection comprising,twomemberseachofwhichhssabailreceivingsccketformcd therein.aball interposed between said hall-receiving sockets, one of said members having formed upon its outer face and concentric with said ball a semispherical surface. a retainingarln securedupononeofsaid members, and an adiusting screw threaded into said retaining arm and engaging the semispherical surface of the other member for maintaining said members in contact with said ball.

3. A power transmitting connection comprising two members each of which has a socket opening into the inner face thereof and provided with a spherical hall-receiving seat, one of said members having formed upon its outer face semisphericsl surface having a radius of curvature in excess of the radius of curvature of said spherical ball-receiving seat, a ball interposed between said ball-receiving seats. and a retaining arm secured upon one of said members and engaging the semispherical surface of the other member for maintaining said members in contact with said ball.

EDWIN W. JOHNSON. 

